Discovery puts flightless-bird theory in a tailspin

WELLINGTON, New Zealand — Research linking New Zealand’s diminutive kiwi with a giant extinct bird from Africa is prompting scientists to rethink how flightless birds evolved.

A report published Friday in the journal Science says DNA testing indicates the chicken-size kiwi’s closest relative is the elephant bird from Madagascar, which grew up to 10 feet high and weighed up to 550 pounds before becoming extinct about 1,000 years ago.

Additional Photos

A skeleton of the adult brown kiwi is displayed next to an egg of a huge elephant bird – the kiwi’s evolutionary sibling, though you’d never know it to look at them. The Associated Press/Canterbury Museum

The authors say the results contradict earlier theories that the kiwi and other flightless birds, including the ostrich and emu, evolved as the world’s continents drifted apart about 130 million years ago.

Instead, they say, it’s more likely their chicken-size, flight-capable ancestors enjoyed a window of evolutionary ascendancy about 60 million years ago, after dinosaurs died out and before mammals grew big.

Those birds, the authors say, likely flew between the continents, with some staying and becoming the large, flightless species we know today.

Alan Cooper, a professor at the University of Adelaide in Australia and a co-author of the paper, said the DNA results came as a huge surprise given the differences in size and location between the kiwi and elephant bird.

“This has been an evolutionary mystery for 150 years. Most things have been suggested but never this,” he said. “The birds are about as different as you can get in terms of geography, morphology and ecology.”

Cooper, a New Zealander by birth, is hoping the paper will also bring him a measure of redemption.

That’s because two decades ago, Cooper and other scientists discovered genetic links between the kiwi and two Australian flightless birds, the cassowary and the emu. That led to New Zealanders believing their iconic bird might have come from Australia, a traditional rival.

The nation’s identity is so entwined with the bird that New Zealanders call themselves kiwis and have also given the name to their currency and the kiwifruit.

But it turns out that if the emu was a cousin to the kiwi, the elephant bird was a sibling. Cooper said it has taken until now for DNA techniques to advance enough to get a usable result from the ancient bones of the Madagascan bird.

Cooper said the bird took its name from Arabic legends that suggested it was so fearsome it could grab an elephant with its talons.

There’s little basis for the legend, given the bird was a flightless herbivore. In fact, it was likely humans that hunted it into oblivion, Cooper said.

Trevor Worthy, a research fellow at Australia’s Flinders University and a paper co-author, said it’s strange the kiwi and elephant bird are such close relatives.

To our readers: We have made a change to comments on this site. Please sign in or register on our new Disqus platform to participate. Questions? Email us.

Here at MaineToday Media we value our readers and are committed to growing our community by encouraging you to add to the discussion.

To ensure conscientious dialogue we have implemented a strict no-bullying policy. To participate, you must follow our Terms of Use. Click here to flag and report a comment that violates our terms of use.